초록

Techniques, apparatus and systems for using Wavelength Modulation Spectroscopy measurements to optically monitor gas media such as gases in gas combustion chambers.

대표청구항 ▼

What is claimed is: 1. A method for optically sensing a gas medium based on Wavelength Modulation Spectroscopy, comprising:modulating a laser wavelength of a tunable laser at a modulation frequency to produce a wavelength-modulated laser beam with a laser frequency range including an absorption band

What is claimed is: 1. A method for optically sensing a gas medium based on Wavelength Modulation Spectroscopy, comprising:modulating a laser wavelength of a tunable laser at a modulation frequency to produce a wavelength-modulated laser beam with a laser frequency range including an absorption band of molecules of a molecular species in the gas medium;directing the wavelength-modulated laser beam that transmits through the gas medium;measuring a transmission of the wavelength-modulated laser beam through the gas medium to obtain measurements of at least one signal at a harmonic frequency of the modulation frequency at different modulation depths in modulating the laser wavelength;processing the measurements of the at least one signal at the harmonic frequency of the modulation frequency at different modulation depths to obtain a total broadening of absorption spectrum of the molecular species in the gas medium,wherein the at least one signal comprises a first signal at a second harmonic frequency of the modulation frequency, andwherein measuring the transmission of the wavelength-modulated laser beam through the gas medium comprises obtaining measurements of a second signal at a fourth harmonic frequency of the modulation frequency at different modulation depths in modulating the laser wavelength; andprocessing the measurements of the second signal to obtain additional information on the gas medium.